Cement set retarding composition and method

ABSTRACT

A HYDRAULIC CEMENT COMPOSITION COMPRISES (A) THE CLINKER CONTAINING 5-60% BY WEIGHT OF   11 CAO. 7AL2O3. CAX2 SP (X REPRESENTS HALOGEN ATOM), MORE THAN 5% BY WEIGHT OF 3CAO.SIO2 SOLID SOLUTION, AND FURTHER 2CAO.SIO2 SOLID SOLUTION AND 4CAO. AL2O3.FE2O3   (4CAO.AL2O3.FE2O3   REPRESENTS   2CAO.FE2O3.6CAO.2AL2O3.FE2O3   SYSTEM SOLID SOLUTION); (B) ANHYDRITE WITH OR WITHOUT HEMIHYDRATE AND (C) AT LEAST ONE OF SULFATES, NITRATES AND CHLORIDES OF POTASSIUM, SODIUM, MAGNESIUM, CALCIUM, ALUMINUM OR AMMONIUM (EXCEPTING CASO4.2H2O, CASO4 AND CASO4.1/2H2O), WHEREBY THE ANHYDRITE IS CONTAINED IN AN AMOUNT THAT AL203/SO3 WEIGHT RATIO OF AL2O3 IN THE CLINKER AND SO3 IN THE ANHYDRITE IS 0.7-1.8 AND HEMIHYDRATE GYPSUM IS CONTAINED LESS THAN 5% BY WEIGHT AS SO3.

HlRosHl UCHIKAWA r-:T AL 3,782,992

CEMENT SET RETARDING COMPOSITION AND METHOD 2 Sheets-Sheet l 10b-89. AU 116 Jan. 1, 1974 Filed Dec. 23, 1971 Jan. l, 1974 HlROsHl UcHlKAwA ETAL 3,782,992

CEMENT .SET RETARDING C'MOSTTN AND METHOD 2 Sheets-Sheet rf.

Filed DBC. 21.3, 1971 1' '2 3 1 s *'1 a Cu(No3)2 CONTENT As No3 A NES 9;

FIG.

i 3 4 '5 s Naci CONTENT As c2 United States Patent O 3,782,992 CEMENT SET RETARDING COMPOSITION AN D METHOD Hiroshi Uchikawa, Funabashi, and Shunichro Uchida, Tokyo, Japan, assignors to Onoda Cement Co., Ltd., Olinda-shi, Yamaguchi-ken, Japan Filed Dec. 23, 1971, Ser. No. 211,307 Claims priority, application Japan, Dec. 29, 1970, 46/ 121,500 Int. Cl. C04b 3/22, 7/00, 13/00 U.S. Cl. 106-315 4 Claims ABSTRACT OF THE DISCLOSURE A hydraulic cement composition comprises (a) the clinker containing 60% by weight of 1 ICaO' 7A1203 CaXZ (X represents halogen atom), more than 5% by weight of 3CaO-Si02 solid solution, and further 2CaO'SiO2 solid solution and 4CaO Al2O3 Fe203 A1203 F6203 represents system solid solution); (b) anhydrite with or without hemihydrate and (c) at least one of sulfates ates d CMEWW' minum or ammoniu excep ing a 4-2 2 a 4 an a 4-/2 2 hereby the anhydrite is contained in an amount that Al2O3/SO3 weight ratio of A1203 in the clinker and S03 in the anhydrite is 0.7-1.8 and hemihydrate gypsum is contained less than 5% by weight as S03.

This invention relates to a hydraulic cement composition, and, particularly, to a hydraulic cement composition which can be suitably regulated of setting time, and which has high strength at the initial and the later stages.

When the mixed raw materials comprising siliceous, and aluminous material as well as a small amount of halide such as uorite, calcium chloride, etc. are sintered, the initial crystallization region of calcium aluminate is extremely narrowed and the clinker obtained will not contain calcium aluminate, but llCaO'7Al2O3-CaX2 as a stable phase, and thus the clinker containing as well as 3CaO-SiO2, 2CaO-Si02, 4CaOAl2O3Fe2O3, etc. is obtained.

llCaO-7Al2O3-CaX2 component has a high hydration activity and a greater hardenability, and the cement containing it develops strength in the initial stage of several hours, and further by incorporation of calcium silicate (especially 3CaO-Si02 solid solution), the hydraulic cement having improved strength development in the early stage (12 hours to 3 days) and later stage is obtained.

The only above-mentioned clinker is flash-setting, and its early strength is low. However, we have found that, if anhydrite (or anhydrite gypsum) with or without hemihydrate (or hemihydrate gypsum) and at least one of the above-mentioned sulfates, nitrates, and chlorides are 3,782,992 Patented Jan. 1, 1974 added to the clinker, setting time thereof is retarded and the improved cement having good workability and excellent strength development property at the initial and the later stages can be obtained.

The object of this invention is to provide the hydraulic cement composition which can be suitably regulated of setting time, and which provides good workability and a high initial strength, and maintains, after mixed with water, a high strength for a long period of time.

Another object of this invention is to provide a method for regulating the setting of the cement.

According to the present invention, there is provided the hydraulic cement composition which comprises (a) the clinker containing 5-60% by weight of 1 ICaO' 7AI203 (X represents a halogen atom), more than 5% by weight of 3CaO'SiO2 solid solution, and further ZCaO-SiOz solid solution and less than 15% by weight of 4G30 'A1203'Fe203 (b)anhydrite with or without hemihydrate; and (c) at CaSO4 ZHZO whereby the anhydrite is contained in an amount that Al2O3/SO3 weight ratio of Al203 in the clinker and S03 in the anhydrite is 0.7-1.8.

As another feature of the present invention there is also provided the method for regulating the setting time and for improving the early and later strength development of the hydraulic cement comprising the clinker containing llCaO-7Al2O3CaX2 (X represents a halogen atom), more than 5% by weight of 3CaOSiO2 and further ZCaO-SiOZ solid solution and less than 15% by weight of 4CaOAl2O3-Fe2O3 and anhydrite with or without semihydrate; whereby the anhydrite is contained in an amount that Al2O3/SO3 weight ratio of A1203 in the clinker and S03 in the anhydrite is 0.7-1.8; the method comprising admixing at least one of sulfates, nitrates and chlorides of potassium, sodium, magnesium, calcium, aluminum or ammonium (excepting CaSO4-1AzH2O, CaSO, and CaSO4-2H2O), in an amount of 0.1-5% by weight as S03 for sulfate, 0.1-7% by weight as NO3 for nitrate, and O.1-7% by weight as Cl for chloride with the abovementioned cement together with water.

The present invention can be more fully understood. from the following detailed description when taken in conjunction with reference to the accompanying drawings, in which:

FIG. 1 shows the relation between the compressive strength of the cement mortar comprising the clinker, anhydrite and NaNO3, and A12O3/SO3 ratio;

FIG. 2 shows the relation between the compressive strength of the cement mortar and potassium alum content;

FIG. 3 shows the same relation as in FIG. 2 when calcium nitrate is added instead of potassium alum; and

FIG. 4 shows the same relation as in FIG. 2 when so dium chloride is added instead of potassium alum.

We have now discovered the methods for improving the early and later strength development and regulating setting time of the above-mentioned cement, and obtained the cement compositions which are satisfactory in workof at least one of sulfate nitrates and n 7 ll n sium sodi u ffective in obtaining good workability of mortar or concrete, and addition of a suitable amount thereof contributes to the improvement of strength development in the initial and later stages.

Also it has been found that addition of an excess amount of these additives not only over-retards setting time but lowers the initial and early strengths, and the resulting cement products are no longer provided with the abovementioned improved proportions. And it has been revealed that in order to realize the characteristics of the cement compositions of this invention, a preferred clinker should contain -60% by weight (unless specifically indicated, percentage is by weight hereinafter) of 11Ca0-7Al203CaX2 (X represents a halogen atom, and the same hereinafter), more than 5% of 3Ca0-Si02 solid solution as the mineral composition thereof and at least one of the above-mentioned sulfates, nitrates and chlorides should be added respectively in an amount of 0.1-5% as S03, 0.1-7% as N03 or 0.1-7.0% as C1 to the clinker when the most excellent results are expected.

It has been found, too, that addition of the above-mentioned additives is not suicient for desirable development of strength, and the combined use of anhydrite is essential. One or more of these sulfate, nitrate and chloride additives can be admixed with the clinker and anhydrite with or without in the hemihydrate state of powder, or can be added thereto by dissolving in a mixing water in a suitable concentration.

Also it has been revealed that, when one or more of the sulfates, nitrates and chlorides are added in the form of powder or a solution in mixing water to the mixture of the above-mentioned clinker, anhydrite and hemihydrate, the initial strength of the cement is somewhat lowered than when hemihydrate is excluded from the mixture, but strength after the early stage is remarkably increased.

As has been explained above, existence of anhydrite is responsible for the initial and later high strength development. The results of our experimental study tell that the strength remarkably develops when anhydrite is mixed in an amount that A1203/ S03 ratio of the amount of Al203 in the clinker and the amount of S03 in the gypsum is 0.7-1.8% by weight. Outside of this range, the strength decreases.

Now the invention is illustrated by practical embodiment.

The clinker was prepared by pulverizing and mixing white clay as a siliceous material, bauxite as an aluminous material, quick lime as calcareous material, uorite as a calcium halide, copper slag as iron source and shaping the resulting mixture and finally sintering it at 1320-1350 C. The thus obtained clinker was ground to powder having Blaine specific surface area of 3700 cm.2/ g. The composition of this clinker analyzed by chemical analysis and by X-ray diffraction analysis are as shown in Table 1.

TABLE 1 Chemical composition (percent):

Si02 17.7 A1203 -T 12.9 F6203 2.4 CaO 62.3 MgO 0.6

Total 95 9 4 TABLE 1.-Continued Mineral composition (percent):

11Ca07Al2O3CaF2 23 3Ca0SiO2 52 In the composition of Table 1, 11Ca0-7A12O3-CaF2 is a component responsible for development of strength in the initial and the early stages, and 3CaO-Si02 is responsible for development of strength at early stage and later stages.

Examples of the additives added to the clinker of Table 1 are shown in Table 2. These substances were ground by a triturator to the same fineness as that of the clinker. Anhydrite and hemihydrate were prepared by the method as explained hereinafter using the starting materials listed in Table 3.

TABLE 2 No.: Additive 1 Aluminum potassium sulfate. 2 Potassium sulfate. 3 Aluminum sulfate. 4 Sodium sulfate. 5 Magnesium sulfate. 6 Ammonium sulfate. 7 Potassium nitrate. 8 Sodium nitrate. 9 Calcium nitrate. 10 Magnesium nitrate. 11 Aluminum nitrate. 12 Ammonium nitrate. 13 Potassiumchloride. 14 Sodium chloride. 15 Calcium chloride. 16 Magnesium chloride. 17 Aluminum chloride. 18 Ammonium chloride. NOTE: All the materials listed in Table 2 ure pure chemicals.

TABLE 3 Ignition loss 21.1 SO2+FC203+A1203 L 1.8 CaO 31.3 S03 45.

Total 993 Natural gypsum having a composition of Table 3 was used to produce the following products.

Hemihydrate: The natural gypsum of Table 3 was kept at C. for 3 hours and was cooled and ground to powder having a Blaine specific surface area of 5,000 cm.2/g.

Anhydrite: The natural gypsum of Table 3 was heated at 700 C. in an electric furnace for 1 hour, and was cooled and ground to powder having a Blaine specific surface area of 3,300 cm.2/g.

These gypsum products were used after the chemical form thereof was determined by thermal analysis such as differential thermal analysis or thermobalance method.

In order to determine the relation between the amount of an additive to be used and the setting time and compressive strength after setting; the setting time and compressive strength of mortar were determined with respect to the cement in which each of the additives of Table 2 was singly mixed, and in which anhydrite was mixed in combination with any of the above-mentioned additives in an amount that Al203/S03 ratio of A1203 in the clinker and S03 in the gypsum is 1.0 by weight.

The initial and final setting time of mortar determined in accordance with the test method for setting of paste described in JIS R5201, using a sample of which the cement/(Toyoura) standard sand ratio is 1:2, and W/C is 0.55.

The compressive strength was determined according to the test method for strength of mortar described in JIS R5201. Thus the relation between the setting time and strength of mortar and the amount of the used additive (NaNO3 as a representative) was determined. The results are shown in Table 4.

range from 0.7 to 1.8. When the ratio is less than 0.7, cracking and crumbling of mortar specimen occur, and

In Table 4, out of many additives of Table 2, the results with respect to only. sodium nitrate are shown. The other additives listed in Table 2 gave the same results as Table 4. That is to say, as the amount of these additives added increases, setting time is retarded. And with increase of the amount of the additive, the compressive strength in the initial stage as well as in the early stage is lowered.

In contrast with the above-mentioned, it has been found that when anhydrite is used in combination with the additive of Table 2, strengths in the initial and later stage develops remarkably, although setting time is prolonged somewhat longer than when the additive is used alone. This fact tells that existence of anhydrite is essential for realization of extremely high initial and later strength.

when the ratio is more than 1.8, development of strength is deteriorated. The same experiments were repeated with respect to potassium alum, sodium chloride, calcium nitrate etc. as setting regulating agent and almost the same results were obtained. Further the same experiments were repeated with respect to cements prepared by mixing the clinker of Table 1 and 15% (on the basis of the weight of the clinker) of anhydrite and 3% (on the basis of the weight of the clinker) of hemihydrate and further adding sulfates, nitrates and chlorides as the additional components. The results of these experiments are shown in FIGS. 2, 3 and 4, and in Table 7.

Table 6 shows the relation between the setting time and compressive strength of mortar when anhydrite and hemihydrate were added to the clinker.

TAB LE 5 Setting time of mortar (mins.) Compressive strength (kga/cm3) Number Additive, amount Initial Final 3 hrs. 6 hrs. 1 day 3 days 7 days 28 days NaNOs 0.3% a5 NCL.-- 8 10 52. 9 109 158 254 304 485 NaNO: 1.0% as NO3 15 20 64.3 186 189 291 311 512 NANO: 5.0% as NO 21 28 60. 5 196 224 256 293 436 NaNOs 8.0% as NO 43 62 13. 4 34. 6 133 169 256 5. MgSO4 0.3% as S03.-. 9 11 73.1 152 309 218 252 425 6. MgSO4 1.0% as SO; 14 18 82.5 135 230 236 295 464 7... MgSO4 5.0% as S03 24 30 79.0 158 198 248 313 504 8.-. MgSOi 7.0% as SO. 53 84 54. 5 112 218 9... CaCl; 0.3% as Cl. 9 13 31. 4 72. 7 196 216 286 507 10.. CaCl; 1.0% as Cl. 16 20 49. 1 80.3 217 225 318 524 11.- CaC'lg 5.0% as Cl. 20 32 61.4 1 224 253 325 512 12.. CaCl? 8.0% as C1. 40 59 20. 6 103 146 283 N Urn-The amounts ol the additives (percent) are based on the weight of the clinker with anhydrite.

In the cement compositions of Table 5, A1203 S03 ratio that is, the ratio of A1303 in the clinker and S03 in the anhydrite was 1.0.

The relation between the setting time and compressive and amount of used additives was studied with respect to the clinkers containing 5-60% of 1lCaO7Al2O3CaX3 and more than 5% of 3CaO-Si02 and further 2CaO-Si02, 4CaO-Al203, etc. The results have revealed that initial setting time can be regulated to the range of about 7-30 minutes, and regulating so is very desirable for realizing good workability and the high initial and later strength when the cement is used as mortar or concrete. Further it has been established that, in order to regulate the initial setting time to 7-30 minutes, the above-mentioned additives should be used preferably in an amount of 0.1- 5% as S03 for sulfates, 0.l-7% as NO3 for nitrates, and 0.1-7% as Cl for chloride.

The results of the study on optimum amount of anhydrite to be added are as follows.

FIG. 1 shows the relation between Al2O3/SO3 ratio and the compressive strength of mortar, when sodium nitrate as a representative of setting regulating agents of this invention was used in an amount of 1.0% as NO3 and various amount of anhydrite was added to the clinker.

By this experiment, it has been established that in order to realize extremely high initial and later strength in the above-mentioned clin-ker, anhydrite should be used in an amount that the Al3O3/SO3 weight ratio is within the TABLE 6 Mixing ratio of gypsums (percent): 1

Anhydrous 3 Hemihydrate 15 Setting time (min):

Initial 12 Final 18 Compressive strength of mortar (kg./cm.2):

3 hrs 85.3 6 hrs. 149 1 days 212 3 days 225 7 days 298 28 days 485 10u the basis of the weight ot the clinker.

In FIGS. 2 to 4, the abscissae respectively represent the amount of potassium alum, Ca( NO3)3 and NaCl added in percentage as S03, NO3 and Cl respectively.

Table 7 shows setting time and compressive strength of mortar for various amounts of the setting regulators, of this invention, that is, potassium alum, calcium nitrate and sodium chloride.

FIGS. 2 to 4 show the relation between compressive strength of mortar and the amount of the setting regulators added. It is apparent that incorporation of sulfate, nitrate, chloride in addition to hemihydrate is remarkably effective for improvement in compressive strength of early and later period.

of a big mixer so as to obtain the clinker having a composition as shown in Table 8.

TABLE 8 Chemical composition (percent) Mineral composition (percent) Free lime 11 CaO-AlzOa-CaXz Clinker SiOz A120: FezOs CBO MgO S05 N820 KzO Total 3Ca0- Si O2 .A 15.9 15.7 2.3 61.9 0.5 1.2 0.08 0.07 97.6 0.2 X=F 27. 51 B 17.8 15.1 2.0 61.5 0.4 1.0 0.03 0.05 97.9 0.1 X=C125 44 No'rE.-Mlnera1 composition was determined by means of X-ray dltraction analysis.

ment in the early and later period is remarkably improved in comparison with the case in which no additives are used. However, there is a limit in the amount of addition of these additives. Generally it is suitable to admix the additives to the range of 0.15% as S03 for sulfate, 0.1-7% as NO3 for nitrate and 0.1-7% as Cl for chloride. And it is essential to regulate so that the initial setting time of mortar is within a range of from 7 to 40 minutes.

The obtained clinker was mixed with gypsums listed in Table 9, sodium chloride, IMQurity 95% or more) and NaN03 (purity a or m re) respectively, and each mixture was tested for setting time and mortar strength by the test methods JIS R5201. The results are summarized in Table 10.

TABLE 7 Setting time oi Amrt o! mortar (mins.) Compressive strength of mortar (kg./cm.2)

a 1 ion Additive (percent) Initial Final 3 hrs. 6 hrs. 1 day 3 days 7 days 28 days l Potassium alum (as S03) 1 25 37 74. 2 162 244 271 325 493 3 14 223 260 312 500 5 12 105 182 247 338 7 42 62. 1 113 184 262 8 95 36. 4 99. 6 171 235 Calcium nitrate (as N00..- 1 18 244 252 313 498 3 20 286 312 370 528 5 17 233 265 343 493 7. 3l 112 175 243 417 8 53 103 167 232 403 Sodium chloride (as Cl). 1 25 182 231 299 4807 3 18 237 275 365 524 5 14 267 303 350 503 7 14 174 204 256 342 8 48 173 193 251 312 Nora-Calcium nitrate was added to mixing water in the form of a solution thereof. The other two additives were added to the clinker in the forni o1' powder.

As has been observed in the above, when anhydrite TABLE 9 with or without hemihydrate is added to cement clinker 1m. in an amount that the ratio of A1203 in the clinker and 40 on G lss S10 A10 Feo COMOs 'rtl S03 1n the anhydrite, that 1s, Al203/S03 ratio 1s between ypsum o z 2 3+ 2 s a g O o a Hemihydrate-. 6.1 1.8 0.9 37.5 0.2 53.6 100.1 0.7 and 1.8 1n accordance with the invention of this ap Anhyd 1.9 l. 0 40.0 0 3 57.2 100A phcation, the strengths of mortar 1n the early and later TABLE 10 Composition Setting of Anhy- Hernimortar (mins.) compressive strength of mortar (kg/cm!) drous hydrate Clinker Additive gypsum gypsum Initial Final 3 hrs. 6 hrs. 1 day 3 days 7 days 28 day (A) 79 NaC1,3 15 24 96.1 (18. 6) 114 (24. 5) 206 (43.6) 256 (50.3) 307 (65.9) 484 (90.6 22 108 (20. 4) 126 (3o. 195 (38. 2) 284 (48.5) 296 (54.6) 438 (85.7 14 24 84.5 (16. s) 156 (34. 5) 212 (42. 4) 258 (51.2) 3 (64.3) 485 (93. 4) 21 43 62.3 (13.4) 105 (22.6) 225 (45.1) 285 (52.7) 336 (65.8) 525 (98. 7) 18 3o 101 (22.4) 125 (29. 6) 221 (47.4) 243 (52.4) 268 (54.6) 467 (87. 7)

llllies in parentheses show bending strength (kg/cm2).

2. The amount of additive is weight 0f used additive. period remarkably develops. In contrast, when a hydraulic cement clinker is merely mixed with water, ilash setting occurs.

From the above explained facts, it is apparent that addition of anhydrite with or without hemihydrate, the salt additive in accordance with this invention contributes to regulation of setting of mortar and improvement of strength in the initial and later period far more than anticipated from the knowledge based on the standard of the prior art. And therefore, this invention makes a great contribution to the cement industry.

Now the invention is illustrated by means of working example.

EXAMPLE White clay, white bauxite, quicklime, copper slag and a small amount of gypsum as well as iiuorite, calcium chloride were ground by a shaft ball mill 85 cm. in diameter and 100 cm. in length, and were mixed by means What We claim is:

1. A hydraulic cement composition consisting essentially of: (a) a clinker containing 5-60% by weight of 11Ca07A1203'CaX2 (wherein X represents a halogen atom), more than 5% by weight of a 3Ca0-Si02 solid solution, and further 2CaOSi02 solid solution and less than 15% by weight of 4CaO-Al2O3Fe203; (b) anhydrite; and (c) at least one compound selected from the group consisting of a potassium, sodium, magnesium, aluminum and ammonium sulfate, nitrate and chloride, a calcium nitrate and a calcium chloride, wherein said anhydrite is contained in an amount such that the Al203/S03 weight ratio of A1203 in the clinker and S03 in the anhydrite is 0.7-1.8, said compound is contained in an amount of O.1-5% by weight as S03 for sulfates, 0.1-7% by weight as NO3 for nitrates and 0.1-7% by Weight as Cl for chlorides, the setting time of (a) being retarded by (b) and (c) and said composition being characterized by a compressive strength of at least 31.4 kg./cm.2 after 3 hours.

2. A hydraulic cement composition as described in claim l, wherein the composition further contains hemihydrate less than 5% as S03.

3. A method for retarding the setting time of a hydraulic cement which comprises:

adding to a clinker together with water a suitable amount of at least one compound selected from the group consisting of a potassium, sodium, magnesium, aluminum and ammonium sulfate, nitrate and chloride, a calcium nitrate and a calcium chloride; and mixing the whole components;

said clinker comprising 5-60% by weight of 1lCaO7Al2O3CaX2 (wherein X represents a halogen atom), more than 5% by weight of 3CaO-Si02 solid solution, 2CaO-Si02 solid solution and less than 15% by weight of 4CaOAl2O3-Fe3O3 and anhydrte in an amount such that the Al2O3/SO3 weight ratio of A1203 in the clinker and S03 in the anhydte is 0.7-

wherein the composition contains hemihydrate in an amount of less than 5% by weight as S03.

References Cited UNITED STATES PATENTS 12/1971 Greening 106-89 2/ 1969 Keenum et al 106--89 2/1969 Keenum et al. 106-89 U.S. Cl. X.R. 

